DNA

Question 1

Chromosome

Answer 1

It’s a molecule that contains genetic material. We have 23 pairs of chromosomes. In each pair, one comes from the mother and the other one, from the father.

Question 2

Locus

Answer 2

It’s the specific position of a gene on a chromosome. For instance, the gene may determine hair, skin or eye color.

Question 3

Alleles

Answer 3

They are variants of the same gene. Returning to the example I gave before, eye color could have different possibilities, there may be a brown allele and a blue one. The dominant allele is the one that will be expressed in the phenotype.

Question 4

Homozygous

Answer 4

We call “homozygous” two alleles that are the same for a particular gene, for example two alleles that both code for brown eye color.

Question 5

Heterozygous

Answer 5

The opposite of homozygous. An individual is heterozygous when the alleles for a gene are different, for example, when someone has one allele that codes for blond hair and the other for black hair.

Question 6

Genotype

Answer 6

It’s the specific combination of alleles that an organism’s genetic makeup has. For instance, we could express a brown eye allele as a capital A and a blue eye allele as a lowercase a. In this case, the eye color genotype would be capital A and lowercase a, one next to the other.

Question 7

Phenotype

Answer 7

It’s the physical or biochemical result of an individual’s genotype. It also involves environmental factors.